“Warning: react-modal: App element is not defined. Please use `Modal.setAppElement(el)` or set `appElement={el}`”

Question

How to fix this warning in console of a React app using the react-modal package:

Warning: react-modal: App element is not defined. Please use Moda

Answer 1

For reference, since it was a pain for me, if you are doing SSR, use the following code to prevent errors server-side:

if (typeof(window) !== 'undefined') {
    ReactModal.setAppElement('body')
}

You could put this in componentDidMount() anywhere you use a modal or I put it in a custom modal component so it's nice and DRY.